Hex to Octal Converter Online

Convert hexadecimal numbers to octal format quickly. See the conversion steps via binary. Useful for legacy systems, certain programming contexts, and understanding number base relationships.

Hex to Octal Converter

Convert hexadecimal numbers to octal (base-8) representation

Show conversion steps

Hexadecimal Input

Octal Output

Common Hex to Octal Conversions

→ 0

→ 7

→ 10

→ 17

→ 20

→ 37

→ 377

100

→ 400

How it works

Enter a hexadecimal number in the input field. The converter first transforms the hex value to decimal as an intermediate step, then converts the decimal to octal (base-8) format.

The conversion handles hex numbers of any length using BigInt arithmetic for full precision. Both uppercase and lowercase hex letters are accepted, with or without the "0x" prefix.

Results display instantly as you type. The octal output uses standard notation (digits 0-7 only), with optional "0o" prefix for programming contexts. Copy results with a single click.

When You'd Actually Use This

Unix File Permissions

Convert hex values to octal for chmod commands and file permission calculations.

Legacy Systems

Work with older systems and documentation that use octal notation for values.

Computer Science Education

Learn base conversion between hex, decimal, and octal number systems.

Embedded Systems

Convert configuration values between formats used by different system components.

Data Encoding

Transform data between encoding schemes that use different number bases.

Debugging

Compare values displayed in different bases across various debugging tools.

What to Know Before Using

Octal digits: Octal uses only digits 0-7. There's no 8 or 9 in octal. Each octal digit represents 3 binary bits.

Hex to octal ratio: Since hex is 4 bits per digit and octal is 3 bits, the conversion isn't digit-to-digit. Go through decimal or binary.

Prefix conventions: Octal may be prefixed with 0o (modern) or leading 0 (traditional C). This tool uses 0o for clarity.

File permissions: Unix permissions like 755 are octal. Each digit represents read(4)+write(2)+execute(1) for user/group/other.

Large numbers: BigInt support means no overflow. Hex numbers of any length convert accurately to octal.

Common Questions

What is 0xFF in octal?

0xFF (255 decimal) is 377 in octal. 255÷64=3 R63, 63÷8=7 R7, giving 377₈.

How do I convert hex to octal manually?

Convert hex to decimal first, then divide by 8 repeatedly, collecting remainders. Or convert hex→binary→octal (group bits by 3).

Why use octal for file permissions?

Octal conveniently represents 3-bit permission groups (read/write/execute). Each permission digit maps to exactly 3 bits, making 7=rwx, 0=---.

Can I convert octal back to hex?

Yes. Use the octal-to-hex converter which performs the reverse transformation through decimal or binary intermediate.

What does 0o mean?

"0o" is the modern prefix indicating octal (base-8) in languages like Python 3. It distinguishes octal from decimal and hex (0x).

Is octal still used today?

Yes, primarily for Unix file permissions and in some embedded systems. Most other uses have been replaced by hex, but octal persists in specific domains.

What is chmod 755 in hex?

755 octal = 1ED hex (493 decimal). But permissions are usually kept in octal since that's how chmod expects them.

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Hex to Octal Converter Online